The present invention relates generally to electronic displays, and more particularly, to electronic displays with switchable holographic optical elements.
Head mounted displays have received considerable attention as a technique for displaying high magnification, large field of view and high definition virtual images. The head mounted display generally includes a support member for mounting the display on a head of a user and various optical and display components. The components are arranged to magnify an image displayed on a compact image display panel such as a liquid crystal display (LCD) and to display the magnified image ahead of the user through the optical system. The user typically does not directly observe an image displayed on a monitor or screen, but instead observes a magnified virtual image converted from the image displayed on the image display panel. The head mounted display thus provides a compact arrangement for displaying to the user a larger image than displayed on a small display panel.
Two current areas of development for head mounted display technology are data display for computer applications and video display for entertainment. Computer displays are typically configured to provide an image field with a 4:3 aspect ratio while video displays are typically configured to provide an image field with a 16:9 aspect ratio. Since the two technologies present different requirements for the displayed image format, two different conventional head mounted display devices are required for data display and video display.
A holographic display system of the present invention is operable to display an image with more than one aspect ratio. According to one embodiment of the present invention, the holographic display system comprises left and right optical systems each comprising an image display operable to display an input image, and first and second holographic devices. The first holographic device is operable to project the input image to overlap with the input image projected from the other of the left and right optical systems to form a resultant image with a first aspect ratio. The second holographic device is operable to project the input image to overlap with the input image projected from the other of the left and right optical systems to form a resultant image with a second aspect ratio, different from the first aspect ratio.
A method according to an embodiment of the present invention is for changing an aspect ratio in a display system. The display system comprises a first holographic system operable to display an image with a first aspect ratio and a second holographic system operable to display the image with a second aspect ratio different from the first aspect ratio. The method generally comprises switching on the first holographic system so that the holographic system diffracts light passing therethrough to form an image with the first aspect ratio and switching off the second holographic system so that the second holographic system allows light to pass therethrough without diffraction thereof
The above is a brief description of some deficiencies in the prior art and advantages of the present invention. Other features, advantages, and embodiments of the invention will be apparent to those skilled in the art from the following description, drawings, and claims.